Why does iterating over GetConsumingEnumerable() not fully empty the underlying blocking collection

Question

I have a quantifiable & repeatable problem using the Task Parallel Library, BlockingCollection, ConcurrentQueue & GetCo

Answer 1

As of .net 4.5, you can create a partitioner which will take only 1 item at a time:

var partitioner = Partitioner.Create(jobsBatchesQ.queue.GetConsumingEnumerable(), EnumerablePartitionerOptions.NoBuffering);
Parallel.ForEach(partitioner, new ParallelOptions { MaxDegreeOfParallelism = (currentTask.ParallelLevel > 0 ? currentTask.ParallelLevel : 1) }, (batch, state) => {//do stuff}

https://msdn.microsoft.com/en-us/library/system.collections.concurrent.enumerablepartitioneroptions(v=vs.110).aspx